View/edit Wiki

Description - describe the bug / feature / suggestion in brief :

Currently there is no repo tab to view the wiki of a repository. Would be nice if that can be browsed too.

I'm unsure if theres support at API for this, maybe checkout https://try.gitea.io/api/swagger and the content API methods noted at #99 .

Expected behaviour - describe what should be the expected result :

• Prio 1 - To be able to browse/show wiki
• To be able to edit/delete/create wiki entriey

GitNex version : 1.2.0/33

Gitea version : 6dbd261

Android version : 9

Screenshots - if any:

Logs - if any :